/**
 * @author   David Simpson david.simpson [at] nottingham.ac.uk
 * @version  1.0 2008-06-18
 * 
 * jGoogleAnalytics - Monitor events with Google Analytics ga.js tracking code
 * 
 * Requires jQuery 1.2.x or higher (for cross-domain $.getScript)
 * 
 * Uses some elements of gaTracker (c)2007 Jason Huck/Core Five Creative
 *    http://plugins.jquery.com/files/jquery.gatracker.js_0.txt  
 *  
 * @param {String} trackerCode
 * @param {Object} options see setings below
 *    
 * usage: 
 *	 $.jGoogleAnalytics( 'UA-XXXXXX-X');
 *	 $.jGoogleAnalytics( 'UA-XXXXXX-X', {anchorClick: true, pageViewsEnabled: false} );
 * 
 *   http://davidsimpson.me/2008/06/18/jgoogleanalytics-google-analytics-integration-for-jquery/
 */

var pGA = Class.create({
	options: {
		anchorClick:         true,         // adds click tracking to *all* anchors
		clickEvents:         null,          // e.g. {'.popup': '/popup/nasty'}
		crossDomainSelector: false,         // e.g. 'a.crossDomain'
		domainName:          false,         // e.g. 'nottingham.ac.uk'  

		evalClickEvents:     null,          // e.g. {'#menu li a': "'/tabs/'+ $(this).text()"}
		evalSubmitEvents:    null,          // e.g. {'#menu li a': "'/tabs/'+ $(this).text()"}
		
		extensions:          [              
											 'pdf','doc','xls','csv','jpg','gif','mp3',
											 'swf','txt','ppt','zip','gz','dmg','xml'		
												 ],	            // download extensions to track
		
		external:	         '/external/',  // prefix to add to external links
		mailto:		         '/mailto/',    // prefix to add to email addresses
		download:	         '/download/',  // prefix to add to downloads
		
		organicSearch:       null,		    // e.g. {'search-engine': 'query-term', 'google.nottingham.ac.uk': 'q'}
		pageViewsEnabled:    true,          // can be disabled e.g. if only tracking click events
		sampleRate:          null,          // e.g. 50 - set the sample rate at 50%
		submitEvents:        null           // e.g. {'#personUK': '/personsearch/uk'}
	},
	/**
	 * load ga.js and add the tracking code
	 */		
	initialize: function(trackerCode, options)
	{
		this.trackerCode = trackerCode;
	  this.options  = Object.extend(this.options, options || {});	
		try
		{
			var gaJsHost = (
			('https:' == document.location.protocol)
			? 'https://ssl.'
			: 'http://www.'
			) + 'google-analytics.com/ga.js';
			var script = new Element('script', { 'src': gaJsHost});
			var gaTrack = function() {
				if (!script.readyState || /loaded|complete/.test(script.readyState)) {
			//		var pageTracker = _gat._getTracker(gaTrackerId);
			//		pageTracker._trackPageview();
					this.setupTracking();						
				}
			}.bind(this);
			script.observe('load', gaTrack);
			script.observe('readystatechange', gaTrack);
			document.body.appendChild(script);			
		} 
		catch(err) 
		{
			// log any failure
			 this.debug('Failed to load Google Analytics:' + err);
		}			
	},
	setupTracking:	function ()
	{
		// Get the tracking code
		this.pageTracker = _gat._getTracker(this.trackerCode);
			
		// Track visitor across subdomain
		if (this.options.topLevelDomain)
		{
			this.pageTracker._setDomainName(this.options.topLevelDomain);
		}
		
		// Set the sample rate - for very busy sites
		if (this.options.sampleRate)
		{
			this.pageTracker._setSampleRate(this.options.sampleRate);
		}
		
		// Track visitor across domains		
		if (this.options.crossDomainSelector)
		{
			// ignore domain names
			this.pageTracker._setDomainName('none');
			this.pageTracker._setAllowLinker(true);
			
			// Add submit event to form selector e.g. form.crossDomain
			$$('form' + this.options.crossDomainSelector).observe('submit', function(form)
				{
					this.pageTracker._linkByPost(form);
					this.debug('crossDomain ._linkByPost');
				}.bind(this)
			);
			// Add a click event to anchor selector e.g. a.crossDomain
			$$('a' + this.options.crossDomainSelector).observe('click', function(anchor)
				{
					this.pageTracker._link( $(anchor).attr('href') );
					this.debug('crossDomain ._link: ' + $(anchor).attr('href'));
				}.bind(this)
			);
			
			// Add click event to link
		}
		
		// Add organic search engines as required
		if (this.options.organicSearch)
		{
			this.options.organicSearch.each(function(pair)
				{
					this.pageTracker._addOrganic(pair.key, pair.value);
					this.debug('_addOrganic: ' + pair.key);
				}.bind(this)
			);
		}
		
		// check that this is the correct place
		this.pageTracker._initData();
		this.debug('_initData');
		
		this.addTracking(this.pageTracker);		
	},
	addTracking: function() {
		// 1. Track event triggered 'views'
		
		
		// loop thru each link on the page
		if (this.options.anchorClick)
		{
			// From: http://plugins.jquery.com/files/jquery.gatracker.js_0.txt
			$$('a').each(function(anchor){
				var u = anchor.href;
				
				if(typeof(u) != 'undefined'){
					var newLink = this.decorateLink(u);

					// if it needs to be tracked manually,
					// bind a click event to call GA with
					// the decorated/prefixed link
					if (newLink.length)
					{
						$(anchor).observe('click', function()
							{
								this.pageTracker._trackPageview(newLink);
								this.debug('anchorClick: ' + newLink);
							}.bind(this)
						);
					}
				}				
			}.bind(this));
		}
		
		// loop thru the clickEvents object
		if (this.options.clickEvents)
		{
			this.options.clickEvents.each(function(pair){
				$(pair.key).observe('click', function(){
					this.pageTracker._trackPageview(pair.value);
					this.debug('clickEvents: ' + pair.value);
					}.bind(this));
			}.bind(this));
		}

		// loop thru the evalClickEvents object
		if (this.options.evalClickEvents)
		{
			this.options.evalClickEvents.each(function(pair){
				$(pair.key).observe('click', function(){
					evalVal = eval(pair.value)
					if (evalVal != '')
					{
						this.pageTracker._trackPageview(evalVal);
						this.debug('evalClickEvents: ' + evalVal);
					}
				}.bind(this));
			}.bind(this));			
		}
		
		// loop thru the evalSubmitEvents object
		if (this.options.evalSubmitEvents)
		{
			this.options.evalSubmitEvents.each(function(pair){
				$(pair.key).observe('submit',function(){
					evalVal = eval(pair.value)
					if (evalVal != '')
					{
						this.pageTracker._trackPageview(evalVal);
						this.debug('evalSubmitEvents: ' + evalVal);
					}						
				}.bind(this));
			}.bind(this));
		}
		
		// loop thru the submitEvents object
		if (this.options.submitEvents)
		{
			this.options.submitEvents.each(function(pair){
				$(pair.key).observe('submit', function(){
					this.pageTracker._trackPageview(pair.value);
					this.debug('submitEvents: ' + pair.value);
				}.bind(this));
			}.bind(this));
		}

		// 2. Track normal page views
		if (this.options.pageViewsEnabled)
		{
			this.pageTracker._trackPageview();	
			this.debug('pageViewsEnabled');
		}
		else
		{
			this.debug('pageViewsDisabled');		
		}
	},

	// From: http://plugins.jquery.com/files/jquery.gatracker.js_0.txt
	// Returns the given URL prefixed if it is:
	//		a) a link to an external site
	//		b) a mailto link
	//		c) a downloadable file
	// ...otherwise returns an empty string.
	decorateLink: function(u)
	{
		var trackingURL = '';
		if (u.indexOf('://') == -1 && u.indexOf('mailto:') == 0)
		{
			// mailto link - decorate
			trackingURL = this.options.mailto + u.substring(7);					
		} 
		else 
		{
			// complete URL - check domain
			var regex = /([^:\/]+)*(?::\/\/)*([^:\/]+)(:[0-9]+)*\/?/i;
			var linkparts = regex.exec(u);
			var urlparts = regex.exec(location.href);
								
			if (linkparts[2] != urlparts[2])
			{
				trackingURL = this.options.external + u;
			} 
			else 
			{
				var ext = u.split('.')[u.split('.').length - 1];			
				var exts = this.options.extensions;
				
				for(i=0; i < exts.length; i++)
				{
					if(ext == exts[i])
					{
						trackingURL = this.options.download + u;
						break;
					}
				}				
			}
		}
		this.debug(trackingURL);
		return trackingURL;			
	},
	debug: function(msg) {
//		console.debug(msg);
//		alert(msg);
	}
});
document.observe('dom:loaded', function() {
	new pGA('UA-577842-1');
});